They don't seem to work with Irssi, though.
/alias cs ^msg chanserv $*
etc
Just doing that can break security on crappy networks (imagine someone is able to get on with the nick 'chanserv', or you're on a network that has no chanserv and without thinking type /cs login mysekretpasswoid...)
Syntac, find yourself dispatch.pl - a script which takes any commands not recognized by irssi and feeds them through to the server directly. Otherwise, if you type a /command and get an error from irssi, prefix it with 'quote'; ie, '/quote cs help' instead of '/cs help'.